Distillation desalination of sea water using heated metal balls to vaporize water



g 5 1969 H. w. NAGEL 3,459,638 DISTILLATION DESALINATIQN OF SEA WATER USING HETED METAL BALLS T0 VAPORIZE WATER F'iled Jan. 24, 1967 BUCKET ELEVATOR nyvsmott HARRY W. NAGEL.

United States Patent 3,459,638 DISTILLAIION DESALINATION OF SEA WATER USING HEATED METAL BALLS T VAPORIZE WATER Harry W. Nagel, West Chester, Pa., assignor t0 Sun Oil Company, Philadelphia, Pa., a corporation of New Jerse y Filed Jan. 24, 1967, Set. No. 611,465 Int. C1. C02b 1/06, C23t 15/00; B01d 3/32 U.S. Cl. 2037 9 Claims ABSTRACT OF THE DISCLOSURE Sea water is distilled in a still by using as the heat transfer medium in the still a moving bed of refractory metal balls. The metal halls are heated then passed into the sea water then removed from the still thus heating the water. Any scale is formed on the metal halls not the surfaces of the still. The scale is removed from the metal halls mechanically and the halls reheated and passed into the solution again.

BACKGROUND OF THE INVENTION A number of methods for desalination have heen devised. These range from simple distillation to eiectric shock treatments.

In a widely-used method called the multi-stage flash method, hot brine is passed through a series of compartments, each successive compartment having progressively 1ower pressure so that as the hot brine passes trom compartment to compartment, it flashes into steam and is cooled on condensers.

Another method employs a spray of molten metal passed into a pool of salt water causing the water to flash, distilling o pure water.

In another method, salt water is subjected to freezing temperatures. The resulting ice crystals are pure water. The crystals are separated from the brine and allowed to melt.

In another method of treating salt water known as reverse osmosis, the water is made to pass through cellu- 1ose acetate membranes under pressure. T he salt does not pass through the membranes and pure water is collected.

In still a further method, an electric current is passed through salt water causing the sodium and chloride in the salt to separate thus leaving pure water to be drawn 0f.

Although as indicated above, there are various modes of separating the dissolved salt from sea water, the most promising trom both ease of operation and economy is generally considered to be some kind of distillation.

One problem that faces distillation methods is the formation of scale which is produced principally from the minerals dissolved in the sea water. The scaling generally occurs on the heat transfer surface and as a result reduces the effectiveness of the heat transfer. The usual method for overcoming scaling is to shut down a distilling operation and physically or chemically remove the scale.

SUMMARY OF THE INVENTION The present invention relates to a process for the desalination of sea water. More particuiarly, the invention relates to a process wherein hot halls of metal are passed through the sea water thereby heating the water to form steam. The metal balls are recovered, the scale which is forrned thereon removed and the halls reheated and recycled to the brine soluton.

The drawing is a diagrammatic representation of one embodiment of the invention showing the relationship 3459638 Patented Aug. 5, 1969 of the cooperating elements of a distillation apparatus and the performance of the process therein.

DESCRIPTION OF THE INVENTION The present invention overcomes the problem of scaling on the heat transfer surface by employing as the heat transfer surface balis of metal. The metal halls are heated generally to a temperature in the range of 500 F. to 2,000 F. and passed into the sea water or brine soluton whereupon they heat the water t0 above its boiling point causing pure potable desalinated water to distill off. The scale forming material in the brine is then deposted onto the heat transfer surface, i.e., the metal halls. The metal halls are subsequently removed from the brine soluton and the scale removed. The halls now are reheated as described above and again passed into the brine soluton. This process can be repeated indefinitely since the scale is formed on the metal halls and subsequently removed outside of the still thus reducing scale formation in the still itseif so that the instant process may be carried on many times longer than any conventional distillation between shut downs for scale removal. The metal halls can be made from stainless steel, titanium, tantalum, or any other refractory corrosion resistant metal.

These and other aspects of the invention will be more fu1ly understood from the following detailed description taken in conjunction with the accompaning drawing which is a diagrammatic scheme illustrating one embodiment of the invention.

Referring to the drawing:

The metal balls 4 pass from hall feed hopper 1 onto endless grate 2 which carries them into ball furnace 3. They are heated to a temperature in the range of 500 F. to 2,000 F., preferably 1000 F. to 1,500 F. From hall furnace 3 the hot metal halls pass through conduit 5 into still 6 where they drop into brine soluton 7 heating the brine solution to above its boiling point. The metal halls are cooled by contact with the brine soluton and passed along the slanted bottom of still 6 to bucket elevator 9 where they are carried out of the brine soluton and deposited in conduit 10. The cooled metal halls pass through conduit 10 onto reciprocating metal grate 11 where the scale is knocked loose from the halls by the action of the grate and the collision of the ba1ls with each other. The scale removed from the halls passes through the grate and is conveniently removed. The halls then pass 0f of the grate 11 onto the endless conveyor belt 12 and are recycled to hall feed hopper 1. The ball furnace 3 can be supplied energy by any suitable means such as gas, oil, coal or atomic fuel. Any 0 gases may be vented to the atmosphere or may be used to preheat the water feed which is fed to the still through conduit 15 and valve 16. The supply of water may be regulated automatically in order to maintain a constant water level in the still 6. The concentrated brine soluton resulting from the distillation is removed through valve 14 and conduit 13 and may be recycled with the water feed or discharged. The discharged brine soluton can be employed as an economically recoverable sonrce of chemicals such as potash, magnesium, bromine, salt, silver and the like because the prevention of the scale formation in the still according to the invention allows the brine solution to be evaporated to very high concentration, whereas in the conventional stills presently in use the scaling problem is accelerated as the brine becomes more concentrated. Steam from still 6 passes through conduit 8 to condensers and storage tanks not shown. Alternatively the steam may be used to preheat the water feed. In order to assure that the steam proceeds through conduit 8 rather than any other of the conduits in the still, it is desirable that a slight vacuum be pulled on the system. The recoverable water is desalinated potable water suitable for consumption or other uses.

As an alternative to the generation of hot gases in the ball furnace 3, they may be generated outside of the hall furnace 3, for example in a dutch oven, turbo compressor, or jet engines such as those used in airplanes which would serve as both compressor and heater.

The rate at which the metal halls 4 are fed from het ball hopper 1 is maintained to be approximately the same rate at which the metal balls 4 are removed from still 6 by bucket elevator 9. This can be done automatically for example with phot sensing devices 01 mechanically by actual observation. The size of the metal halls 4 is not particularly critical; however, it is preferred that the diameter of the metal halls be in the range of 0.5 inch to 1.5 inches. This is principally for case of handling and availability. F0r practical operation, the diameters of the halls should be substantially uniform. The water level 7 in still 6 should be maintained at approximately 10 to 100 times the average diameter of the halls.

It is understood that the procedure as described above merely represents one embodirnent and that it is within the skill of those in the art to apply the novel process set forth herein to apparatus of other and different design.

In order to obtain optimum equipment life, it is preferable that the metal parts that would otherwise be exposed during the process be of a corrosion resistant nature such as those described for the halls.

The prncipal advantages of the instant invention over prior processes for the production of potable water are that the equipment has far 1ess down time for equivalent amounts of water produced than comparable equipment employing more conventional processes and the availablity of a concentrated brne solution for recovery of chemical components.

The invention claimed is:

1. The method of desalination comprising (a) heating metal halls to a temperature in the range of 1,000 to 1,500" F.

(b) passing the het solid metal halls into a solution of salt in water at atmospheric pressure,

(c) vaporizing, the water at atmospheric pressure without further heat and condensing the vapor to distillate and (d) removing the cooled metal balls ftom the solution of salt in water.

2. The method according to claim 1 wherein desalinated water is recovered.

3. The process according to claim 2 wherein deposits on the metal halls are removed and the metal hall recyoled into step a,

4. The method according to claim 3 wherein the metal halls are corrosion resistant.

5. The method according to claim 4 wherein a concentrated salt solution is removed from the distillation zone and a fresh feed of less concentrated solution of salt in water is added to the distillation zone.

6. The method of desalination according to claim 1 wherein a highly concentrated solution of salt in water is recovered.

7. The method according to claim 1 wherein the metal halls have a diameter in the range of 0.5 inch to 1.5 inches.

8. The method according to claim 7 wherein the diameters of the metal balls is substantially uniform.

9. The method according to claim 8 wherein the depth of the water is in approximately 10 to times the diameter of the average diameter of the metal halls.

References Cited UNITED STATES PATENTS 2,601,102 6/ 1952 Dickey. 2796,237 6/ 1957 Nettel. 2,905,596 9/ 1959 Findlay 20372 3242975 3/ 1966 Kogan 2037 X 3,272,335 9/ 1966 Nettel -106 X 3305455 2/ 1967 Loebel 2037 3,335083 8/ 1967 Tibball 202-235 X FOREIGN PATENTS 701,544 12/1953 Great Britain.

608,014 7/ 1926 France.

664,792 1/ 1952 Great Britain.

NORMAN YUDKOFF, Primary Examiner F. E. DRUMMOND Assistant Examiner U.S. Cl. X.R. 

